Stabilization of lactonitrile



2,830,073 Patented Apr. 8, 1958 In addition, the composition is stabilized with respect 2 830 073 to dissociation of lactonitrile, which is surprisingly less in the treated composition than it is in both an un- STABILIZATION F LACTONITRILE treated composition and one in which only an acid is employed. The stabilized composition need not be treated g zgg ggzg ggi ggggg z fi gg 5 prior to use, although if it is desired to do so, the acid and water contents may be readily removed. 53%: Company New York a corporation The following example illustrates the invention.

No Drawing. Application October 12, 1956 EXAMPLE 1 Serial 615,451 The A. P. H. A. number of distilled lactonitrile (LN) is determined and then 50 gram samples prepared, one 8 Chums- 260-465) of which contains neither acid nor water. The remaining samples have water and acid contents as shown in This invention relates to the color stabilization of lacto- Table I. The samples are then bottled and capped, nitrile. More particularly, it relates to a method for stored at room temperature in a dark cabinet and obinhibiting the formation of color in lactonitrile and to served periodically for color development. At the end the color-stabilized lactonitrile so obtained. of fourteen months storage, the A. P. H. A. number of Lactonitrile has been found useful as an intermediate each bottled sample is determined.

Table I Total Sample LN CHBOOOH H3P04 H10 pHin Initial Final HON N0. (gm) (1111.) (inl.) (1111.) 10%,, A..P.H.A.A.P.H..A. deid as so. percent in the preparation of organic compounds, for instance We claim: ethyl t and Potentially useful In vanous other 1. A method of color stabilizing lactonitrile and minifields i potentlal. usefulness however i .never mizing the dissociation thereof which comprises adjusting been i q for vanou? Feasons among whlch is the the hydrogen ion concentration of lactonitrile to a pH color instability of lactonitrile. On storage forextended less than about 35 measured on a 10% solution of Penods even 111.1116 absence of hght lactommle has lactonitrile in water by incorporating in said lactonitrile been found to discolor to such an extent as to render a suflicient amount of an acid Selected from the group it unsuited for .Difierent batches lacmnitfile consisting of acetic and phosphoric, and adding water develop color at l tpi discoloranon 1S a 40 to said lactonitrile in amount of at least 0.5% on the problem characteristic of lactonitrile in general. waight of the lactonitrile.

It is the principal object of this invention to provide a A method according to claim 1 in which the PH is color-stable lactonitrile composition capable of withadjusted to about and the water content is not standing extended periods of storage and/or shipment more than about 5% without excessive discoloration. It is a further object A method acco'rding to claim 2 in which the acid is of this invention to provide such a color-stable composiacetic tion without the use of costly addition agents and which A method according to claim 2 in which the acid is meets established standards of purity. phosphoric.

These objfa'cts have been met m a 51mph yet 5. A color-stable lactonitrile composition comprising Plately f P the method of lactonitrile having incorporated therein an acid selected Pmsmt mYentlon compflses q g the hydrogen Ion from the group consisting of acetic and phosphoric in colfcentranon of a Punfied lactommle Product free P amount sutficient to provide a pH less than about 3.5 resldual reaciants F fby t F of when measured on a 10% solution of lactonitrile in Phosphonc and and umfonfllx d1SPersmg therem water, and at least 0.5% water on the weight of the a controlled amount of water. This simple operation pro- 55 lactonitri1e vides a olo Stabilizing efiect lasting long i fi 6. A composition according to claim 5 in which the The amount of acld added 9 the Pumfied lactommle pH is about 2.0-3.5 and the water content is not more may vary. It should be sufiicient, however, to reduce than the pH to at least about 3.5 when measured on about a A composition according to claim 5 in which the 10% solution in Water. While the pH may be adjusted to acid is acetic considerably less than 3.5, no additional advantage is 8. A composition according to claim 5 in which the gained by going below about 2.0. The preferred range, acid is phoSphon-c therefore, is about 2.03.5 measured on a 10% solution of lactonitrile in water.

The water content of the stabilized composition may References cued m the file of thls patent also vary. In general, it should be greater than about UNITED STATES PATENTS 0.5% on the weight of the lactonitrile and usually will 2,416,624 Hansley Feb. 25, 1947 be greater than 1% varying to as high as 5%, although 2,537,814 Davis Ian. 9, 1951 more than 5% appears to provide no added advantage.

The composition resulting from the above described FOREIGN PATENTS treatment may be stored for a considerable period of 481,624 Canada Mar. 11, 1952 time without being rendered useless by discoloration. 691,269 Great Britain May 6, 1953 

1. A METHOD OF COLOR STABILIZING LACTONITRILE AND MINIMIZING THE DISSOCIATION THEREOF WHICH COMPRISES ADJUSTING THE HYDROGEN ION CONCENTRATION OF LACTONITRILE TO A PH LESS THAN ABOUT 3.5 MEASURED ON A 10% SOLUTION OF LACTONITRILE IN WATER BY INCORPORATING IN SAID LACTONITRILE A SUFFICIENT AMOUNT OF AN ACID SELECTED FROM THE GROUP CONSISTING OF ACETIC AND PHOSPHORIC, AND ADDING WATER TO SAID LACTONITRILE IN AMOUNT OF AT LEAST 0.5% ON THE WEIGHT OF THELACTONITRILE. 